The present invention relates to devices for depositing thin films, and, in particular, relates to a sputtering source.
The sputtering apparatus may be an open-ended cathode and an anode structure in an evacuated chamber typically containing less than 1 Torr pressure of an ionizable gas. A DC or RF source causes the target material to have a net negative charge (i.e., being the cathode) which pulls positively charged ions out of the plasma. These ions impact the target material causing atoms, ions and small (possibly ionized) atom clusters to be ejected from the target surface. This ejected material is free to move through the surrounding gas and deposit upon any surface that it encounters, in particular, a substrate material upon which this depositing material will form a film. This material deposits on a substrate located either within or outside of the sputtering source.
In one prior sputtering device, U.S. Pat. No. 4,060,470, the cathode is a conical structure having a large opening toward the substrate so as to provide a relatively wide angle of emergence of the sputtered material. The use of magnetic and electric fields provides additional control of the sputtering materials.
Another prior sputtering device, U.S. Pat. No. 4,842,703, uses magnetic and electric fields as well as a cathode structure having a flat bottom and conical sides for coating the substrate uniformly. The angle of the conical sides from the vertical is very large.
Another prior sputtering device, U.S. Pat. No. 4,100,055, uses a cathode having an outer, middle and inner portions to control the ions.
The following U.S. Patents are incorporated by reference: U.S. Pat. Nos. 5,194,131; 5,024,747; 4,909,314; 4,842,703; 4,834,860; 4,657;654; 4,673,480; 4,179,351; 4,100,055; and 4,060,470.